Among older former cigarette smokers, a strong correlation was shown between smoking duration and health, with longer smoking history associated with greater risk for poor overall health, chronic obstructive pulmonary disease (COPD), and chronic disease, according to CDC research.

In national data, for people ages 65 and older who had once smoked but quit, a linear association was seen between years of active smoking and risk for fair or poor health, reported Ellen A. Kramarow, PhD, of the CDC in Atlanta, in National Health Statistics Reports.

Based on data from the 2018 National Health Interview Survey (NHIS) and adjusted for age, sex, race, and Hispanic origin and education, the analysis linked several negative health outcomes with increasing smoking duration:

• Poor or fair health: 17.8% (smoking duration ≤10 years), 20.3% (>10 and <25 years) , 23.4% (25 to <40 years), and 28.5% (≥40 years)
• COPD: 9.1%, 12.2%, 20.3%, and 32.7%
• At least four chronic conditions: 18.1%, 17.2%, 23.3%, and 26.1%
• Limitations on social life: 8.6%, 9.1%, 10.7%, and 14.2%

Kramarow told MedPage Today that while the health benefits of quitting smoking are numerous and well characterized, less is known about the health risks associated with smoking in the past among older former smokers.

Older adults in the U.S. are more likely than younger adults to have a history of smoking, with former smokers making up 21% of the 2018 NHIS population overall, and 40% of survey participants who were ages 65 and older. This 40% represented nearly half of men in the 65-plus age group and a third of women.

Quitting smoking is associated with immediate and long-term health benefits, such as improved lung function and reduced risk of heart attack and stroke.

Among the former smokers, ages 65 and older, who participated in the 2018 NHIS, more than half reported smoking for 25 years or more, with 23.5% smoking for 40 or more years, and 31% smoking for 25 to 40 years.

Some 18% reported smoking for less than a decade, and 27.6% reported smoking for more than 10 years and less than 25 years.

Roughly three-fourths of the older former smokers had started smoking by age 20, and 93% of those who smoked for less than a decade reported quitting 40 years earlier or more.

Conversely, among older former smokers who smoked for 40-plus years, 37.4% reported quitting within the last 5 years, and 57.3% reported quitting more than 5 years and less than 25 years before participating in the 2018 survey.

The analysis divided the older former smokers into four smoking duration categories: 10 years or less, more than 10 years and less than 25 years, 25 to less than 40 years, and 40 years or more.

Kramarow noted that the study had significant limitations, including the inability to control for how long ago a former smoker quit. Smoking length was established based on answers to the questions; “How old were you when you first started to smoke fairly regularly?” and “How long has it been since you quit smoking cigarettes?”

“There may be independent effects of time since quitting on health among older adult former smokers,” she wrote. “Measured at one point in time, it is difficult to separate the impact of number of years smoked from time since quitting because they are so highly correlated.”

Information was also lacking on the intensity of smoking — whether the former smokers had been light or heavy smokers. The survey also did not ask about use of other tobacco products.

Despite the limitations, Kramarow told MedPage Today that the findings bolster evidence of a dose-response relationship between smoking and poor health, and she said clinicians caring for older patients should ask about smoking history.

“When considering the health of older people, it is worth keeping in mind that a significant proportion are former smokers,” she said. “Smoking history is probably still relevant, even if someone stopped smoking decades ago.”